SCS Financial and its subsidiary, SCS Capital Management, an RIA based in Boston and New York City with $16.5 billion in assets under management, are joining Focus Financial Partners, a network of independent wealth management firms, Focus announced Monday.

The addition is the largest to date for Focus, which has seen rapid growth over the last few months with the addition of 10 new partners added so far this year.

SCS was founded in 2002 by Pete Mattoon, Tony Abbiati and Doug Ederle and focuses on ultra-high-net-worth clients. The transaction expands Focus’ presence in the ultra-high-net-worth space, Focus says. Active in 18 states, SCS has 77 employees including 37 advsiros.

In April, Focus announced the private equity firms Stone Point Capital and KKR were obtaining a majority interest in the company, which they valued at $2 billion. Rudy Adolph, founder and CEO, and the rest of his team maintained their leadership positions.

Since then, Focus also announced a partnership with Bordeaux Wealth Advisors, a wealth management firm based in Menlo Park, Calif., that caters to ultra high-net-worth individuals and families. The partnership helps both firms to expand their presence in the West Coast among the ultra wealthy, the firms said. the firm has $1.9 billion in assets under management and acts as a family office for many of its clients.